Method of cooling the air in underground mine workings and like places



Oct.9, 1945. w R F LUNT 7 2,386,560

METHOD OF'COOLING THE AIR IN UNDERGROUND MINE WORKINGS AND LIKE PLACES Filed Feb. 12, 1940 3 Sheets-Sheet 1 f RV P Pump F m jg 1945. w. R. F. LUNT METHOD OF COOLING THE AIR IN UNDERGROUND MINE WORKINGS AND LIKE PLACES Flled Feb 12 1940 3 Sheets-Sheet '2 Zinnentor attorney Oct. 9, 1945. w. R. F. LUNT 2,336,560

METHOD OF COOLING THE AIR IN UNDERGROUND MINE WORKINGS AND LIKE PLACES Filed Feb. 12, 1940 I s Shegts-Sheet s .exchanginggmeans to extract heatfmm the mine by the'iadiabatic expansion of mean-entering Patented Oct. 9, 1945 GROUND PLACES-j METHOD. oi ooonmor THE AIR. IN UNDER:

MINE onxmes "AND ;jwmaa m man en Lunt, permanen i v M Unionof Sbuth Africa Application-February 12, 1940, Serial N6,-

. In the Union of South Africa Fcbruary'17 1939- recl ims. (o1. e 1in This invention relates .toan improved method of cooling the air in underground mine workings and is particularly applicable to deep mines .where high temperatures are the rule. Q According to. an earlier application it is-pron5 posed positively to evacuate dust-ladeni-air from v .m-ine Workings :by means of a suction @conduit system arrangedto extend iii-om the surface to the underground shafts and working places. The

throughout the mine and each branchis provided at spaced intervals with valve 'controiled openings which openings are arrangedat the lower points or depressions in the workings towards which the dust particles rmrrmallytend-to gravitate The meansat' the surface for creating a partiai vacuum in the-conduit system may comprise anevacuating pu-mp or the like.

Accordingly the present invention consists in =w1u he understood V that/the drop in temperature through adiabatic expansion-will also take 'placein the ducting forming the conduit system, and this ductin will be constructed and arranged in such a manner that it acts effectively to assist cooling the mine air. According toth-e method ofv the present invention air in the underground workings'of a mine is';cooled by heat exchange with'air drawn'from the bottom or l-ower said conduit' system branches in all directions to) --leyels- "upward-1y in oont-radistinction to known methods where cooling is efiectedrby heat exchange with air drawn fromsthesuriace downthe provision offa suction conduit system extending from the surface to the underground shafts and working places, means at the surface for evacuating air from said conduit system so as to create a partial vacuum therein, means -in apertures to cause controlledadiabatic expansion of the constantjent opy or isentrcpic process type, of the mine air into the conduit system to cool it and utilising the conduit system as'heat air in contact therewith, whereby the-workings are cooled by air drawn. the bottom T01 lower levels upwardly. By mine-air is meant the ai-r in the shaft or d-rives' 'SLl-I IObl-IidiMihE. con-i,

am. By exhaust all, as the :tenm is hereinafter em ploy'edin'the specification and claims, I mean the vitiated; mine air as it -is-drawn from the mine exteriorly of the conduit system, into the conduit system and is there subjected to a se a 2 querice of thermal processes.

- "More particularly it is proposed to insert in the: conduit: system large expansion chambers whereby due to the drop in temperaturecaused the chambers; cooling of the mine air; surrounding and passin in contact with saidexpans-ion 'chaiirbeis is effected by a transfer of" heat from the mine air to the air being evacuateds These expansion chambersare provided atin the form of restricted resistance-creating inlet? In applying the invention it isproposed that, Where aseries of pipes converge, incoming air is arranged to pass around the piping for purposesof being cooled.- v i a According qtpresentpractice dust-laden air is withdrawn from mine workings by means of exhaust trunking which terminates inthe mine workingsin'dust-coliecting chambers. i y

According to the present invention control ..valves and. heat gexchangers are suitably intergspersed Von all: exhaust trunking "extending from these dust-collecting chambers sothat the adiabatic expansion of the urine air as it. passes -:=l-,-hrough thesepassages wili give a degree of coolcan system, and'which. is available to the working whiohis communicated to'the mine air. I Qnali exisitingmine ventilation systems 'of the suction type. control; valves, Venturi ducts and like meansforyredumng' or throttling the air flow are employed to cause a slight degree of expansion and so give a cooling effect. Suction heads or filtering-heads may or may not be contained in a suctionexhaustsystem inca ses where valves are in enistence 'tor controlling the air inflow. V. .7 7

0n all existing exhaust conduitswefiectiveheat extraction may be increased -by-painting ;-such conduits black and; providing them a Air resistance by means The-exhaust trunking is further provided with reducin air intake :apentureswhere requiredfor acontrol-ling air eicparisionl Such apertures are preferably in the form of replaceable nozzles .havin astreanwlined -.inte1ti=or shape to reduce friotionlosses.

of-filtering and suction heads may becreated i-nthe suction system so as intentionally to restrict the new oif air for expansion purposes.

The air expansion chambers or heat exchangers included in .a suction system are provided with means for extracting condensed moisture which is lialole to collect therein; fiuch means may surfacstoensure the maximum transferwofaheatf 5 consistecif water-collecting; chambers D W d with the necessary stop cocks or valves for isolating such chambers for drainage purposes.

In order to increase the degree of suction in the dust-collecting chambers air ejectors operating from the existing compressed air conduit may be employed. Fans may be embodied in the exhaust conduit not so much as boosters but as means to localise the vacuum effect or sub-atmospheric pressure for air expansion purposes.

The invention also includes the provision in existing or new ducting of a valve orvalves arranged for automatic opening or closin whereby intermittent expansion of air is obtained. The

said valve or valves may be arranged to .be controlled thermostatically or their opening randclosing may be arranged to depend upon the degree of suction or velocity of the air entering alternatively a risein mine temperature may be arranged to cause a partial opening of the valve or valveswhereby the expansion will be greater but the removal of air lessened. In this latter case, owing to the volume of air removed being reduced, the British thermal units extracted will of course be lessened and the temperature of the workings will rise.

In an alternative embodiment an electrically operated vibrator valve governed by an electrically operated governor of the ball type may be employed in such a manner that its'speed would control the valve for opening and closing the duct as desired. t

It is to be understood that the present invention is applicable to existing ventilation systems as well as to new installations.

A suction is created by pump 55 disposed on the surface of the ground. The mine air entering by this opening is restricted or throttled by the Ven turi throat 5 whereafter it expands into the expansion chamber or heat exchanger 6, provided with fins 1 toincrease its efficiency.

In Figure lb a slightly difierent f orm of heat exchanger is shown at 8. In this case the opening 9 causes throttling of the inflowing mine air by being made relatively smaller than the chamber .8. 'To provide means for controlling the deree of partial vacuum in the chamber 8, a booster fan or blowerlfl is arranged in series with the ducting I.- A vacuum gauge ll indicates the degree of vacuum being obtained.

In Figure 1c alternatively a nozzle 50 controlled by'a valve or cook 5| may be used to control expansion of mine air into the suction conduit -I which will itself then act as heat exchang- To enable the invention to be more clearly understood and carried into practice, reference is now made to the accompanying drawings in which like reference numerals denote like parts throughout the several Views.

Figs. la-ldillustrate diagrammatically applications of the invention to the underground workings of a mine.

Fig. 2 is an elevation of an improved construction for the ventilation ducting.

Fig. 3 is an'end section taken on line III-III of Fig. 2.

Fig. 4 is an elevation of an expansion chamber or heat exchanger. v

Fig. 5 is an elevation of amodified construction of expansion chamber or heat exchanger.

Fig. 6 shows a spring-regulated control valve.

Fig. 7 shows a thermostatically-controlled valve.

Fig. 8 shows a modified form of thermostatically controlled valve.

Fig. 9 shows a valve controlled for intermittent opening and closing by electrical means, and

Fig; 10 shows a valve controlled by the de-.

gree of suction or velocity of inflow of mine air.

Referring to the drawings, Fig. 1a, reference I denotes a branch of the suction ducting extending down a shaft 3 into 'an underground working 2. One inlet for mine air is shown. at 4.

ing means. 7

In another embodiment shown in Figure 1d a filtering head 53 controlled by a valve 54 may be arranged so that'the fitlering medium provides sufilcient resistance to inflow to cause the entering mine air to expand for purposes of cool in the suction conduit I.

To facilitate the transfer of heat, the suction ducting may be constructed in the manner shown in Figs. 2 and 3, in which the walls are corrugated or fluted in a longitudinal direction to increase their effective area.

Fig. 4 illustrates one form which an expansion chamber or heat exchanger may take. As shown it is connected to the suction ducting by the pipe l2 while the inlet apertures for the mine air are shown at l3 and I4. Valves I2a, I31; and Ma. are provided to regulate the rate of inflow and outflow and consequently the degree of cooling obtained. Vacuum gauges I5 and I6 indicate the actual degree of vacuum at the inlet and outlet sides respectively. The vertical pipes l1 and I8 are connected by a series of horizontal smaller bore cross pipes l9 provided with fins 20. The lower ends of the pipes l1 and I8 lead into a duct and moisture-collecting chamber 2| supplied withdrain cocks 22. The isolating valves 23 and 24 are provided to enable the chamber to be drained when necessary.

Fig. 5 illustrates another form which a heat exchanger may take. In this case vertical pipes 25 and 26 are connected by small bore cross pipes 21 and top and bottom pipes 28 and 29.

The bottom pipe 29 constitutes the dustand moisture-collecting chamber and for this purpose is provided with the drain cocks 30. Mine air enters by the aperture 3| and the apparatus is connected to the suction ducting by the pipe 32 controlled by the valve 33. A valve 34 controls the inlet aperture 3|.

Figs. 6 to 10 illustrate various constructions to provide for the automatic opening and closing of valves controlling the inflow of mine air to the suction ducting 40. In Fig. 6 a valve 35 is arranged to be opened against the action of a compression spring 36. In Fig. 7 a valve 3'! is arranged to be opened thermostatically by expansion of the heat sensitive coil 38; In Fig. 8 a butter-fly valve 39 is controlled thermostatically by a heat sensitive spiral 4!. In Fig. 9 a butterfly valve 42 is arranged to be opened intermittently by an electrically operated vibrator coil 43, co-operating with a contact 44' fixed to an arm 45 actuating the valve 42. And lastly, Fig. 10 shows a gate valve 46 controlled by a governor 41 actuated by a wind vane 48 located in the 'neeaseo tacts ith'em, to exhausted. g 5. Apparatus for cooling the airin an undernuetmg on. These constructions are given ib'y way of -:exa;mple and are not intended to limit the invention to these :particular methods of "valve control. r What Irclaimis:z I

I 1: In localizing the co'olin'g of air prevailingat selected places in the drives a mine working which working 'iinoludes a :main shaft and dnves 'ektending'therefrom, the lmethodwhich 'comprisesin combination; the steps of drawing a stream of ennaust air the drives into-a;prin- ;cipa1 Prone "ofilower ressure through branch zones --1ocated in-said. drives and discharging air flour said pr pal zone -outside of th'e s'aid worktransferring :heatnom and reducing "the temperature of the air prevailing in said "selected places by causing the stream of exhaust aiir' in 'eaoh tiran'ch zone to undergo a controlled adia- -:ba'tic expansion adjacent each selectedplace, V "and causing heat exchange, while said exhaustair is cooled as a result of such expansion, be-

"tween the 'air prevailing in such selected place and the cooled and expanded exhaust airji n the particular branch zone associated therewith.

2; an improved "method or cooling the airin a-n underground working, comprising drawing,

fthrough a-suctionventilat i ng conduit system dis- -p'o'sed; in said working, apartial' vacuum from the region of the outlet of said working and there y, at selected points in the working, and by said vacuum, drawing the air into saidfco'nduit system, and expanding it, in a controlled adiabatic process, thereby reducing the temperature of the airfand, at selected points within said Working, facilitatingheattransfer from the air exteriorly of the conduit system to the expanded thelatter, to cool said exterior air. V

An improved method -of"cooli-ng"the air in "an underground working having an opening or "outlet to the surface, comprising orawiag,

"*throiigha suction ventilating conduit "system disposed "in said working and having onebr more heat exchange Zones disposed at desired "points v therein, a partial vacuum fromt-he region of said heat transfer "from th'e .air -'ext eriorly of t duit system' 'to'the expanded and cooled air within the latter, to 0001 said exterior air.

4. Apparatus for cooling the air in an underground working; having an opening or outlet to the surface of the ground, comprising a conduit system extending from said outlet into said working; air-evacuating means connected thereto near said outlet for evacuating exhaust air from the system so as to create a partial vacuum in the system; one or more heat-exchange means provided in said conduit system at a point or points within the working where it is desired to localize the cooling of the air in said working exterior to said conduit system; and means, having stream-lined interiors, and providing openings on the up-stream side of said heat exchange means, for causing a controlled adiabatic expansion of the air drawn therethrough into the said heat exchange means, thereby appreciably lowering the temperature of the air which is being exhausted, the heat-exchange means serving to transfer the heat of the air exterior thereto, and which conthe expanded and cooled ibe'in'g :g mund "working; having an opening or outlet to the surface of the ground; comprisin aconduit --system extending from said outlet intos'aid working; air-evacuating rmeans connec'ted thereto near said outlet for evacuating exhaust air from the system, so as to create 'apartial vacuum therein; one or more heat-exchange means provided insaid conduit'system'at 'a point or points within the working where it is "desired to localize the cooling of the air in'rsaid working exterior to said conduit system, said heat-exchange means having 1tota1'cross=sectional "areas "substantially increased over that "of :the' i'emain'derof the conduiti system,'and having large surface areas, for active heat transfer; andmeans, having streamlined interiors, and pro'vi'dir'ig "openings on the "up-stream side of said heat-'exchange'means, for

' causing a =cor' 1 trolled a'diabaticexpansion of the ing; air-evacuating meansconnected*theretoinear said outlet ror evacuating exh ust air from the system, so to 'create "a partial vacuum in the fair "drawn therethrough' into the said heat-exchange :rneans, thereby appreciably lowering the temperatureortne air which is being exhausted, the neat-'exohangemeans servin to transrer the heat of t e air extenar tnereto, and which "contacts them-tome xpanded and cooled "air being exhausted. V

16'. Apparatus ioriooolin'g the air in an underving'an opening or outlet to the surface or the ground, comprising a conduit system extending from said outletinto saidworks'ystein; one ormore heat-exchange means provideo in said conduit system at a point or pomts "within the working where :it is desired to localize the cooling of the air in said working exterior to the conduit system; id' heat-exchan e-means having "total cross-sectional areas substantiauy increased over that of-tne remainder ofth'e consuit system, and hav' i g large sd'rface areaa' for active he'at trans-fem Water-collecting "chambers "connected to said heat-exchange means for collecting condensedmoistur'e; means forisolating said chambers from the restof the system, to permit drainage; andmfeans, having stream-dined interiors, and providing openings onthe upstream side of said heat exchange means for causing a controlled adiabatic expansieno'f the air drawn theretnrcngn into' tn heat-e3;-

enange' means, thereby appreciably lowering the temperature of the airwhich is being exhausted, the heat-exchange means serving to ti an'sfefthe neat-of the air exteriorthereto, and which contaots thorn, to the expanded and comes air being exhausted.

'7. Apparatus for cooling the air in an underground working, having an opening or outlet to the surface of the ground, comprising a conduit system extending from said outlet into said working; air-evacuating means connected thereto near said outlet for evacuating exhaust air from the system, so as to create a partial vacuum in the system; one or more heat-exchange means provided in said conduit system at a point or points Within the working where it ,is desired to localize the cooling of the air in said working exterior to said conduit system; means, having stream-lined interiors, and providing openings on the up-stream side of said heat-exchange means, for causing a controlled adiabatic expansion of the air drawn therethrough into the said heat-exchange means, thereby apr 10. Apparatus for cooling the air inan under- ,ground working, having an opening or outlet to 'preciably lowering the temperature of the air which is being exhausted, the heat-exchange means serving to transfer the heat of the air points.

: 8. Apparatus: for'cooling'the air in anunderground working, having'an opening or outlet'to 10 the surface of the ground, comprising a conduit system extendingjrom said outlet into said work- "ing; air evacuating means connected thereto near said outlet for evacuating exhaust airfrom the system, so as to create a partial vacuum in the system, said conduit system being externally modified at one or more points along its length within thexworking substantially to localize the heattransfer from the neighboring air in said workingexteriorto saidsystemy and-.120

means, having streamlined interiors, providing openings on theup-streamside-of themodified portion or portions of said conduit system,-for

causing a controlled adiabatic expansion-of the air drawn therethrough' into the said modified portion or portions of the conduit system, thereby appreciably lowering the temperature, of the air which is being exhausted, the modified-portion' orportions ofthe conduit system'serving to transfer the heat of the air exteriorthereto, and

which contacts'it, to the-expanded and. cooled air being exhausted. a i

9. Apparatus for cooling the air in'an under ground working, having anopening or outlet to the surfaceof the ground, comprising a conduit system extending from said outlet into said working; air-evacuating means connected thereto near said outlet for evacuating exhaust air from thesystem, so as to create a partial vacuum therein, one or more heat-exchange means having-exteriorly disposedheat-absorbing fins provided in said conduit system at point or points within the working where it is desired to localize vthe cooling of the air in said working-exterior to said conduit systemiand-means, having stream-"- linedinteriors, and providing openings on theupstream side of said heat-exchange means, for causing a controlled adiabatic expansion of the ail drawn therethrough into said heat-exchange A means, thereby appreciably lowering the tentperature of the air which is being exhausted, the heat-exchange means serving to transfer the heat of the air exterior thereto, and whichcontacts them, to the expanded and cooled air being A exhausted.

the surface of the ground, comprising a conduit system extending from said outlet into said working; air-evacuating means connected thereto near said outlet for evacuating exhaust air from the system, so as to create :a partial Vacuum therein; one or more-heat-exchange means exteriorly black in color provided in said conduit system at point or points within the working where it is desired to localize the cooling of the air in said working exterior to said conduit system; andmeans, having stream-lined interiors, and providing openings on the up-stream side of said heat exchange means, for causing a controlled adiabatic expansion of the. air, drawn therethrough into the said heat-exchange means, thereby appreciably lowering the temperature of the air which isbeing exhausted, the heatexchange means serving to transfer the .heat of the air exterior thereto, and which contacts them, to the expanded and cooled air being exhausted. l1.- An improved method of cooling the air-in 1 an underground mine working comprising drawing, through a suction ventilating conduit system disposedin said working, .a partial vacuum from the. region of the outlet of said working and thereby, at selected points in the working'and by said vacuum, drawing the atmospheric air and its existing water vapour content into said conduit system, and expanding said air, in a controlled adiabatic process, thereby :reducing the temperature of the air, and at selected points Within said working, facilitating heat transfer from the air exteriorly of the conduit system, to the expanded and cooled air within the latter, to cool said exterior air. I

12'. Apparatus for cooling the air in an underground working, having an opening or outlet to the surface of the ground, comprising a, conduit system extending from, said outlet into said working; air-evacuating means connected thereto near said outlet for evacuating exhaust air from the system so as to create a partial vacuum in-the system; one or more heat-exchange means provided in said conduit system at a point or points where it is desired to localize the cooling of the air in said working exterior to said conduit system; and means for causing a controlled adiabatic expansion of the air drawn therethrough into said heat exchange means, thereby appreciably lowering the temperaturefof the air which is being exhausted, the heat-exchange means .serving to transfer the heat of the air exterior thereto, and which contacts them, to the expanded and cooled air being exhausted WILLIAM R. F. LUNT. 

